1. 8-28-12 Math 7  Bellwork #2  Please have the following on your desk: Name Tag Math book HW Red Pen Pencil

2. 1-3 EVALUATING EXPRESSIONS p.13 You can EVALUATE a variable expression by replacing each variable with a number. Then use the order of operations to simplify.

3. EXAMPLES  Evaluate 14 – 10 + 8 Use order of operations to first subtract, then add. This numeric expression simplifies to 12.  Evaluate 4y – 15 for y = 9. Replace the variable with 9 and rewrite the expression as 4(9) -15. Then use order of operations to simplify to 36 – 15 and simplify again to 21.

4. Try This  63 – 5x, for x = 7  4(t + 3) + 1 for t = 8

5. Try This  63 – 5x, for x = 7  4(t + 3) + 1 for t = 8 28 45

6. EXAMPLE 2  Evaluate For a = 2, b = 5 and c = 10 Substitute and rewrite the expression: Then simplify: 3(2)(5) + 5 6(5) + 5 30 + 5 35

7. “Try This p.13”  3) 6(g + h), for g = 8 and h = 7  4) 2xy – z, for x = 4, y = 3 and z = 1  5) For r = 13 and s = 11

8. Try This  6(g + h), for g = 8 and h = 7  2xy – z, for x = 4, y = 3 and z = 1 For r = 13 and s = 11 90 23 12

9. Example 4  An online music store charges $14 for each CD. Shipping costs $6 per order. Write a variable expression for the cost of ordering CDs. Then find the cost of ordering 4 CDs. $14 for each CD plus $6 shipping. 14n + 6  For four CDs, 14(4) + 6 Simplify: 56 + 6 = 62

10. HOMEWORK P. 15 #1-9 all, 11-29 odd